I've actually been thinking about doing the basecoat a silver or light grey over the black primer, and then rather than painting on the purple markings, applying them with a *sponge*.
It might take a little experimentation, but I thought it might give it kind of that mottled look without going on too heavy. Seems like if you found the right sponge it might have a nice effect, anyway, something a little different. And then I might do a little drybrushing in either grey or another shade of purple. I'll have to look at a good picture of the WS again to decide what shades to go with.